The development of a standard model of cosmological structure formation over the last forty years must count as one of the great success stories in Physics. The model describes the geometry and material content of the Universe, explaining how structure – galaxies of various sizes and types, groups and clusters of galaxies, the entire cosmic web of filaments and voids – emerged from a hot and near-uniform Big Bang. In this issue the article Dark matter and cosmic structure by Carlos S. Frenk and Simon D. M. White (pp. 507–534) reviews the standard model of cosmic structure formation, focusing on the nonlinear processes that transformed the near-uniform universe that emerged from the Big Bang into the highly structured world we observe today. The image shows the warm dark matter halo at z = 0 of the Aquarius simulations (Aq-A). The figure is roughly 1.5 Mpc on a side.